Automatic dishwasher

ABSTRACT

In an automatic dishwasher of the type wherein tablewares are soaked in water and are than washed, there are provided an impeller for producing a whirling stream of water in the washing tub and a timer for performing the programmed operation of washing, rinsing and drying steps.

United States Patent [151 3,698,406 Sato et a1. 1 1 Oct. 17, 1972 [54] AUTOMATIC DISHWASHER 3,130,737 4/1964 Jellies ..1134/57 D [72] Inventors: Hide Sam, Nagoya; Kunihiko 0, 3,182,854 5/1965- Ge11er.-..; ..211/41 X (fifwken both ofjapan 3,316,925 5/1967 Schroeder ..134/95 3,344,804 10/1967 Lyman ..134/57 DX [73] Assignee: Tokyo Shibaura Electric Co., Ltd., 3,378,933 4/1968 Jenkins ..134/107 X Kawasaki-shi, Japan Primary Examiner--Edward L. Roberts {22] Filed 1971 Attorney-Flynn &Frishauf I21] Appl. No.: 106,660 1 [57] ABSTRACT [52} U.S.Cl ..134/57 D, 134/107, 134/188 In an automatic dishwasher of the type wherein [51] Int. Cl. ..B08b 3/02 tablewares are soaked in water vancl are than washed, [58] Field of Search..134/57 D,57 DL,58 D,58 DL, there are provided an impeller for producing a 134/95,107, 115 184,186, 188;211/41, whirling stream of water in the washing tub and a i 181 timer for performing the programmed operation of i washing, rinsing and drying steps.

[56] References Cited 1 UNITED STATES PATENTS 12 Claims, 13 Drawing Figures 2,478,814 8/1949 Ferris ..134/57 DL UBUUUUUUU Win es PATENTED 17 I97? 3.698.406

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TIMER CYCLE CHART CONTACT oNE COMPLETE ROTATIONAL CYCLE OF'6 IMPULSES NQ SOAK WASH RINSE DRY OFF 2o so MINUTES [1 OPEN CLOSED 1 AUTOMATIC DISHWASHER BACKGROUND OF THE INVENTION With this construction it is not possible to uniformly project the water jet against various dishes. For example, dishes on the back of other dishes which directly receive the water jet can not be washed thoroughly. Moreover, when designing and manufacturing the rotary spray arm care should be taken to decrease as far as possible the dead angle of the water jet. Even with a careful design, it is difficult to obtain uniform and efficient washing effect. The water jet vigorously impinging upon not only the dishes but also the inner wall of the tub results in noise. Moreover the dishwasher of this type requires pumps for circulating and draining water and motors for driving the pumps. This construction of course requires pipings between the pump and the spray arm thus complicating the construction and increasing the cost of manufacturing. Circulation of the water through the tub and spray arm causes the small jet orifices to be clogged by small remnants of foods. Although a filter is included in the circulation path of the water for the purpose of removing such remnants, such filter would then be clogged thus requiring frequent cleaning thereof. This is not advantageous from the standpoint of maintenance.

SUMMARY OF THE INVENTION It is an object of this invention to provide an improved dishwasher wherein dishes and, tablewares and the like disposed in a tub are washed and/or rinsed by a whirling action, or flow of water created by an impeller whereby to wash and/or rinse uniformly the dishes and to decrease noise.

Another object of this invention is to provide a novel dishwasher which is not required to be equipped with any filter, water circulation pump, spray arm and pipings interconnecting these elements thus simplifying the construction of the dishwasher.

A further object of this invention is to provide a novel dishwasher which is simple and compact.

Another object of this invention is to provide a dishwasher which can wash dirty tablewares in shorter operating time of the impeller thus decreasing the power consumption of the driving motor of the impeller.

Still another object of this invention is to provide a dishwasher provided with a novel dish cage which can efficiently accommodate tablewares of various sizes and configurations.

A further object of this invention is to provide a dishwasher having a cage which can be placed horizontally when removed from the washing tub.

Another object of this invention is to provide a novel control device for the dishwasher which, in response to the water level in the washing tub, performs the programmed sequence of washing, rinsing and drying steps.

Another object of this invention is to provide a novel dishwasher having an improved hot water supply means which can not only supply hot air to the washing tub for drying washed tablewares but also effectively cooling the driving motor of the impeller.

According to a preferred embodiment of this invention tablewares contained in a washing tub are washed by a whirling action of water rather than water jets as in the conventional dishwasher. The whirling stream sweeps past all portions of the tablewares without any dead angle and can avoid noise as well as splash. A pressure switch responsive to the water level in the washing tub is provided to control a timer which per-v forms programmed steps of dipping, washing, rinsing and drying. A cage for containing tablewares to be washed has a stepped bottom to accommodate tablewares of different shapes and sizes. One or more small auxiliary containers may be disposed in the cage to contain articles of small size. A driving mechanism for driving the impeller is contained in the spaces below the stepped bottom and side wall of the tub to minimize the physical dimensions of the washer.

BRIEF DESCRIPTION OF THE DRAWINGS:

device;

FIG. 6 is an enlarged view of a door switch;

FIG. 7 is a plan view, partly in section, of the water supply device and the door switch shown in FIGS. 5 and 6, respectively; I

FIG. 8 is a plan view to show. the manner of accommodating dishes and the like in the tub;

FIG. 9 shows a perspective view of a wire. cage or dish supporting rack; 1

FIG. 10 is an enlarged perspective view of a portion ofthe cage; I J

FIG. 11 is a perspective view, partly broken away, of an auxiliary container for small articles;

FIG. 12 is a connection diagram for electrical componentsutilized in the dishwasher; and

FIG. 13 is a timer cycle chart to explain the operation of the dishwasher.

DESCRIPTION OF THE PREFERRED EMBODIMENT:

cabinet by means of mounting pieces 3. The bottom of the tub 4 is stepped; the right hand half 5 is raised whereas the left hand half 6 is recessed and is provided with a drain port 14. Spaces 8 and 9 are defined respectively between the raised bottom portion 5 and the bottom of the cabinet 1 and between side walls of the tub 4 and cabinet respectively. An impeller 10 is rotatably mounted on the raised bottom portion 5 through bearing means 1 1 for creating a whirling stream of water for washing and/or rinsing dishes and the like. A driven pulley 13 is secured to the shaft 12 of the impeller in space 8. A driving motor 15 and a pulley 17 mounted on the motor shaft 16 are contained in the other space 9, the, pulleys 13 and 17 being operatively interconnected by a belt, thus rotating the impeller 10 by the motor. As best shown in FIG. 4, the motor 15 is secured to the bottom plate 19 of the cabinet 1 through antivibration rubber washers 21 and a supporting frame bolted to the bottom plate. The pulley 17 is secured to the lower end of the motor shaft 16 whereas a fan 18 is secured to the upper end thereof for supplying hot air as will be described hereinafter. An inspection opening 22 is formed through a side wall of the cabinet, which is normally closed by a removable cover 23.

The hot air supply device comprises a horizontal casing mounted above the motor 15 and is formed with an air intake opening 24 at its bottom, the fan 18 being contained in the casing 25 and surrounded by an air guide 26. A heater 27 including an electric heating wire 28a wound about an insulating plate 28 is disposed in the casing 25 closely adjacent to the fan guide 26. An air pipe 29 communicating with the washing tub 4 is connected to one end of the casing 25 adjacent to heater 27, as shown in FIG. 4.

As shown in FIGS. 3 and 4, a pressure switch 30 is also contained in space 9 to be operated by the variation in the water level in the washing tub 4. More particularly, when the water level reaches the normal level W FIG. 2, the hydrostatic pressure of the water in the tub 4 compresses the air in an air trap 32 communicated with the depressed bottom 6 of the tub 4 via a connecting pipe 33 and the compressed air actuates the pressure switch 30 via an air tube 31 connected to pipe 33. Operation of the pressure switch closes an electromagnetic valve 48 to stop the water supply as will be described later in more detail.

As shown in FIGS. 3 and 4, a drain electromagnetic valve 34 is secured in the bottom of the cabinet 1 through a bracket 35. The drain valve 34 is of the three way type with one opening connected to the drain port 14 of the washing tub 4 via a pipe 39, the other one connected to a drain pipe 37 extending to the outside of the cabinet while the remaining one connected to an overflow port 38 positioned near the overflow level W FIG. 2, at the upper portion of the tub via an overflow pipe 39.

As shown in FIG. 3, a timer 40 is also contained in space 9 which is operated by a dial knob 41 on the outside of the cabinet to automatically programming, water supply, washing, draining and drying operation steps in co-operation with the pressure switch 30. As shown in FIG. 1, a pilot lamp 43 is mounted on a panel 42 to indicate various steps of operation.

The upper end of space 9 is closed by a generally flat flange 44 which is contiguous to the upper edge of side wall 7 of the washing tub 4 and slightly inclined toward it as shown in FIGS. 2 and 5. A hollow casing 45 is pro 'jected above flange 44 to contain a portion of a water feed device and a door switch. As best shown in enlarged views of FIGS. 5 and 7, a water feed nozzle 46,

an electromagnetic valve 48 and a pipe 47 interconnecting these two elements are contained in casing 45,

the inlet end of the electromagnetic valve 48 being connected to a source of hot water, not shown, through a coupling 50 and a pipe 49 shown by dot and dash lines.

As shown in FIGS. 6 and 7, the door switch comprises a resilient diaphragm 51, of rubber for example, and is mounted in an opening through the upper wall of casing 45, a rigid operating rod 52 connected to the thick central hub portion of diaphragm 51 and a switch 54 supported by a bracket 53 depending from the upper wall of casing 45 and arranged to be operated by the door 56 of the dishwasher. The operating member 55 of switch 54 is disposed to abut against or close to the lower end of the operating rod 52 when the switch is opened.

Door 56 is liquid tightly mounted on the top of the washing tub 4 through a gasket 64. More particularly, as shown in FIGS. 1 and 4, the rearedge is pivotally mounted on the rear upper edge of cabinet 1. By means of hinges 57 and a handle 59 co-operating with a catch 58 secured to the front upper edge of the cabinet is pivotally mounted on the front edge of door 56..An exhaust lid 60 having a plurality of vent openings 61 is removably mounted on the upper surface of door 56 so that when the lid 60 is removed water can be filled in the tub. Immediately beneath lid 60 is provided a baffle plate 62 for preventing splash of the water. An operating member 63 is secured on the inside surface of door 56 to be urged against the hub of the diaphragm 51 for closing switch 54 when the door 56 is closed.

A dish cage 65 is fabricated from steel wires and is constructed to accommodate a plurality of types of tablewares. The deep portion 66 of the cage positioned close to the deeper bottom of the tub is adapted to contain large dishes 67 whereas the shallow portion 68 close to raised bottom 5 of the tub smaller tablewares such as glasses 69, tea cups 70 and small dishes 71, as shown in FIGS. 2 and 8. To mount horizontally the cage 65 in the tub 4 on its stepped bottom, supporting bars 72 and 73 are secured on the bottom. (only two are shown in FIG. 2) As best shown by the enlarged views of FIGS. 9 and 10, two horizontal cross bars 74 and 75 are provided for supporting bar 73. A substantially L-shaped supporting frame 76 is pivotally mounted on cross-bar 74 whereas a narrow U-shaped clip 77 made of resilient material, a leaf spring for example, is mounted on the other cross-bar 75. When positioned upright, as shown in FIG. 9, the lower end of the supporting frame 76 is positioned at substantially the same level as the shorter supporting bars 72 on the deeper bottom of the tub permitting to rest the cage 65 on the flat floor. The supporting frame 76 is also provided with two cross-bars 78 and 79, with the former confronting the opening of the resilient clip 77. Thus, when cross-bar 78 is resiliently caught by clip 77, the rotatable supporting frame 76 is fixed to the vertical position thus stabilizing the cage 65. When the supporting frame 76 is rotated or folded into the horizontal position shown in FIG. 2 it can be held in that position by means of a resilient clip 81 secured to any one of the frames of the shallow portion 68 of dish cage 65.

A small grid shaped auxiliary container 82, made of synthetic resin for example, is disposed in cage 65 to contain small articles such as forks and spoons 83. Similar small rectangular container 84 is also disposed in cage 65 to contain small articles that float on water.

The container 84 is provided with hinged doors at its upper surface and upper portion of one side thereof as shown by the enlarged view of FIG. 11, so that not only relatively long articles but also very short articles can be readily put in container 84.

Turning now to FIG. 12 showing an electric circuit utilized in the novel dishwasher, power terminals 86 and 87 connected to a source of supply, not shown, are connected to one terminal of door switch 54 and a power line 88, respectively, The other terminal of door switch 54 is connected to one contact 90 among a plurality of contacts 90 through 96 of a timer 40 which are opened and closed according to a time chart shown in FIG. 13 by the rotation of a timer motor 89. Pilot lamp 43 is connected across contact 90 and power line 88 and the neutral terminal of pressure switch 30 is also connected to contact 90. Normally closed contact 97 of pressure switch 30 is connected to power line 88 through one stationary contact 95 and the electromagnetic valve 48 for feeding water, the other stationary contact 94 being connected to contact 90. Normal open contact 98 of pressure switch 30 is connected to power line 88 via timer motor 89 and contact 91 and a motor 15 for driving fan 18 and impeller are connected in series across motor 89. The common juncture between timer motor 89 and contact 91 is connected to contact 90 via contact 96. Further, contact 92 and electromagnet 34 for drain are connected in series across contact 90 and power line 88. A series combination of contact 93 and heater 28 is also connected across contact 90 and power line 88.

The operation of the dishwasher will be described with reference to the time chart shown in FIG. 13. Various contacts are in the condition shown in FIG. 12 when the dish washer is not operated.

' l. Soaking step Various tablewares to be washed are put in the cage 65 in the tub 4. A suitable quantity of detergent is added and the door 56 is closed. Then knob 41 is operated to set timer 40 in operation whereby various contacts thereof are brought in the conditions shown in the column SOAK in the chart of FIG. 13. Under these conditions, contacts 90 and 95 are closed to light pilot lamp 43 and since no water has been poured in the tub 4, contact 97 of pressure switch 30 will be closed. Then electromagnetic valve 48 is energized through closed contacts 90, 97 and 95 to feed hot water (hereinafter termed as washing water) into tub 4 from the source of hot water, not shown, through valve 48, pipe 47 and nozzle 46. When the level of the washing water reaches the normal level W sufficient to soak tablewares in cage 65 the compressed air in air trap 32 operates the pressure switch 30 to transfer its movable contact from contact 97 to 98, thereby energizing timing motor 89 and deenergizing electromagnetic valve 48 to stop the supply of hot water. Concurrently therewith timer motor 89 is energized through contact 90 and contact 98 of pressure switch 30 to initiate counting operation of the set time. Since at this stage contact 91 is opened so that motor and hence impeller will not be rotated.

2. Washing step.

The timing operation proceeds with the rotation of the timing motor 89 until the predetermined soaking step has finished. At this time the washing step is initiated and various contacts will assume the conditions depicted in theWASl-I column in FIG. 13. More specifically, contacts and are still being closed and contact 91 is now closed to energize motor 15 to rotate fan 18 and impeller 10 to create a whirling'flow of the washing water, which is effective to wash the tablewares contained in the cage. During this step too, contacts 90 and 98 of the pressure switch 30 are maintained closed to continue to energize timer motor 89 to count the set time. Of course, the electromagnetic valve 48 is deenergized to interrupt water supply. Fan 18 draws air through intake opening 24 immediately above motor 15 to pump air into washing tub 4 through pipe 29 and the air thus sent into tub 4 is discharged to outside through vent openings 61. through exhaust lid 60. This flow of air serves to cool the motor 15.

3. Rinsing step As the timing operation by timer 40 proceeds further, the washing step is terminated and the rinsing step is commenced. At this time, various contacts of the timer assume the conditions shown in the column RINSE. More particularly, contacts 91 and95 are opened whereas contacts 92 and 96 are closed. Opening of contact 91 deenergizes motor 15 whereas closure of contact 92 energizes electromagnetic valve 34 to drain the water in tub 4. As the water isdrained the water level is lowered to transfer the movable contact of pressure switch 30 from contact 98 to contact 97. At this time, since electromagnetic valve 48 is being deenergized by the opening of contact 95, no water is fed. However, timer motor 89 continues to count by the closure of contact 96.

When the timing operation proceeds until the water is completely drained from the tub, contacts 92 and 96 are opened whereas contacts 91 and 94 are closed. Opening of contact 92 deenergizes timer motor 89. Of course, timer motor 89 is also deenergized by the opening of contact 96. However, only the electromagnet 48 is energized to feed rinsing water. I

When the level of the rinsing water reaches the normal level W contact 98 of the pressure switch 30 is closed to energize again motor 15 to drive fan 18 and impeller 10, to rinse the tablewares by the whirling action of water. At the same time, timer motor 89 is also energized to resume the timing operation for rinsing for a predetermined interval of time. Since rinsing water is continuously fed through electromagnetic valve 48 during this period, the level of the rinsing water exceeds the level W and then reaches overflow level W Then the surplus water overflows through overflow opening 38, pipes 39 and 37 to the outside of the cabinet. Thus, used water is supplemented by fresh water to efficiently rinse the tablewares for a prescribed interval.

Thereafter, similar operation is repeated, that is, contacts 92, 96 and 91, 94 are opened and closed alternately which co-operates with the operation of the contact 98 of the pressure switch 30 whereby the cycle of water drainwater feed-rinsing with water feed and overflow is repeated and thus the rinsing operation is performed again for a predetermined interval. And then the timing operation proceeds until the above described drainage is operated thus finishing the rinsing operation.

4. Drying step Upon completion of the rinsing step, the timer 40 now proceeds the drying step in which contacts of the timer assume the conditions shown in the column D- RY" in FIG. 13. More particularly, closure of contact 93 energizes heater 28 through contact 90 and closure of contacts 90, 96 and 91 energizes motor 15. Contact 96 also energizes timer motor 89 to proceed the timing operation.

As above described, motor 15 drives impeller 10 in tub 4 and fan 18 in casing 25 to supply hot air heated by heater 28 into tub 4 through pipe 29. The hot air supplied into the tub 4 is stirred by rotation of impeller 10 to effect uniform drying of the washed tablewares. After a predetermined time, contacts 90, 93, 96 and 91 are opened to complete all programmed steps. Thus, pilot lamp 43 is extinguished and all contacts of the timer are restored to the condition shown in FIG. 12.

Thus, this invention, provides a novel dishwasher wherein a process step is provided during which tablewares are merely soaked in water for a desired time interval. In this step, almost all of the dirts on the tablewares are removed by dissolution or brought into a condition of easy removal so that the succeeding washing step may be of short interval. This reduces the operating time and the power consumption of motor 15. in addition, since fan 18 for supplying hot air and the impeller 10 are driven by a commonmotor 15, it is possible to simplify the construction of the dishwasher. Moreover, as the air drawn past motor 15 during its operation of washing, rinsing and drying steps effectively cools the motor thus enabling to use a motor of relatively simple construction not having its own cooling fan. In addition the heat derived from the motor preheats the air thus increasing the efficiency of the hot air utilized for drying.

Moreover, as the rinsing is performed by overflowing dirty water while fresh rinsing water is being continuously supplemented thus not only improving the efficiency of the rinsing operation but also decreasing the rinsing time.

The bottom of the washing tub 4 is stepped to define a space between the raised bottom portion 5 and the bottom of cabinet for accommodating the pulley for driving the impeller, thus reducing the height of the cabinet. Moreover all driving mechanisms for the impeller including motor 15 and driving pulley are contained in the side space 9 so that it is possible to miniaturize the cabinet 1 and hence the dishwasher.

Provision of a cage having a stepped bottom enables to accommodate tablewares of different sizes and configurations. The whirling stream of water created by the impeller uniformly washes all portions of the tablewares without forming any dead angle and'noise which have been inherent to conventional dishwashers utilizing jet streams of water. This also eliminates a water circulating pump, a filter, connecting pipes and troubles accompanying these elements, thus contributing to the miniaturization of the dishwasher. Foldable supporting frame 76 enables horizontal mounting of the cage 65 when it is taken out from the tub. Use of auxiliary containers 82 and 84 permits washing of small 7 gent prior to the soaking step and to operate for a short time the impeller to dissolve the detergent in the washing water, whereby to increase the washing efficiency. Further, it is possible to use a pressure switch which is operated directly by the hydrostatic pressure of the water. I

Thus the novel dishwasher can wash efficiently various types of tablewares without noise and with minimum number of moving elements.

What we claim is:

l. A dishwasher comprising I a cabinet, a washing tub disposed in said cabinet and adapted to contain tablewares tov be washed beneath the surface of cleaning water within the tub, an impeller in said tub to create a whirling flow of said water substantially entirely submerging said tablewares and utilized for washing said tablewares, 7

means to rotate said impeller to create said whirling flow, and

control means for effecting washing and rinsing, said washing tub having a stepped bottom including a deeper bottom portion and a raised bottom portion, said impeller being mounted on said raised bottom portion.

2. A dishwasher comprising a cabinet,

a washing tub disposed in said cabinet and adapted to contain water, and tablewares to be washed,

an impeller in said tub to create a whirling flow of said water utilized for washing said tablewares,

means to rotate said impeller, and

control means for effecting washing and rinsing, said control means comprising a pressure switch responsive to the water level in said washing tub having reached a level at which said tableware is at least substantially submerged within the water, and

a timer cooperating with said pressure switch and having a plurality of contacts which are opened and closed sequentially at predeterminedtime intervals for performing in succession water feeding to said level, washing, rinsing and draining steps.

3. The dishwasher according to claim 2 wherein a feed water electromagnetic valve is provided at the upper portion of said cabinet and water drainage electromagnetic valve is provided at the bottom of said cabinet, both of said electromagnetic valves being controlled by said pressure switch and said timer to feed water until said level is reached and drain water.

4. The dishwasher according to claim 1 wherein a cage adapted to contain tablewares to be washed is removably mounted in said washing tub.

5. The dishwasher according to claim 4 wherein said cage has a stepped bottom of the shape conforming to said stepped bottom of said washing tub, and a foldable supporting leg is provided for the raised bottom portion of said cage.

6. The dishwasher according to claim 5 wherein said foldable supporting leg comprises a frame pivotally connected to said raised bottom portion of said cage so that said frame can be rotated to the vertical position for placement of said cage on a horizontal support surface when it is taken out from said washing tub.

7. The dishwasher according to claim 4 wherein said cage further comprises a first auxiliary container adapted to contain relatively heavy weight small articles and a second auxiliary container adapted to contain relatively light weight small articles that float on the water.

8. The dishwasher according to claim 7 wherein said first and second auxiliary containers are in the form of rectangular cages, each being provided with lids covering the upper surface and the side surface thereof.

9. A dishwasher comprising a cabinet,

a washing tub disposed in said cabinet and adapted to contain water and tablewares to be washed at a level to substantially totally immerse said tablewares,

an impeller in said tub to create whirling flow of said water for washing said tablewares,

driving means to rotate said impeller,

control means for effecting washing and rinsing, and hot air supply means mounted above said driving means and taking in air which had circulated past said driving means to supply hot air into said washing tub to dry said tablewares which have been washed and rinsed in said washing tub.

10. The dishwasher according to claim 9 wherein said hot air supply means comprises a casing including an air inlet port immediately above said driving means and an air exhaust port at one side of said casing, a fan contained in said casing and operatively connected to said driving means, an electric heater contained in said casing to heat air through said air inlet, and a conduit extending between said air exhaust port and washing tub for supplying thereto the air heated by said electric heater.

11. The dishwasher according to claim 1 wherein said cabinet is provided with a door on its upper surface, 

1. A dishwasher comprising a cabinet, a washing tub disposed in said cabinet and adapted to contain tablewares to be washed beneath the surface of cleaning water within the tub, an impeller in said tub to create a whirling flow of said water substantially entirely submerging said tablewares and utilized for washing said tablewares, means to rotate said impeller to create said whirling flow, and control means for effecting washing and rinsing, said washing tub having a stepped bottom including a deeper bottom portion and a raised bottom portion, said impeller being mounted on said raised bottom portion.
 2. A dishwasher comprising a cabinet, a washing tub disposed in said cabinet and adapted to contain water, and tablewares to be washed, an impeller in said tub to create a whirling flow of said water utilized for washing said tablewares, means to rotate said impeller, and control means for effecting washing and rinsing, said control means comprising a pressure switch responsive to the water level in said washing tub having reached a level at which said tableware is at least substantially submerged within the water, and a timer cooperating with said pressure switch and having a plurality of contacts which are opened and closed sequentially at predetermined time intervals for performing in succession water feeding to said level, washing, rinsing and draining steps.
 3. The dishwasher according to claim 2 wherein a feed water electromagnetic valve is provided at the upper portion of said cabinet and water drainage electromagnetic valve is provided at the bottom of said cabinet, both of said electromagnetic valves being controlled by said pressure switch and said timer to feed water until said level is reached and drain water.
 4. The dishwasher according to claim 1 wherein a cage adapted to contain tablewares to be washed is removably mounted in said washing tub.
 5. The dishwasher according to claim 4 wherein said cage has a stepped bottom of the shape conforming to said stepped bottom of said washing tub, and a foldable supporting leg is provided for the raised bottom portion of said cage.
 6. The dishwasher according to claim 5 wherein said foldable supporting leg comprises a frame pivotally connected to said raised bottom portion of said cage so that said frame can be rotated to the vertical position for placement of said cage on a horizontal support surface when it is taken out from said washing tub.
 7. The dishwasher according to claim 4 wherein said cage further comprises a first auxiliary container adapted to contain relatively heavy weight small articles and a second auxiliary container adapted to contain relatively light weight small articles that float on the water.
 8. The dishwasher according to claim 7 wherein said first and second auxiliary containers are in the form of rectangular cages, each being provided with lids covering the upper surface and the side surface thereof.
 9. A dishwasher comprising a cabinet, a washing tub disposed in said cabinet and adapted to contain water and tablewares to be washed at a level to substantially totally immerse said tablewares, an impeller in said tub to create whirling flow of said water for washing said tablewares, driving means to rotate said impeller, control means for effecting washing and rinsing, and hot air supply means mounted above said driving means and taking in air which had circulated past said driving means to supply hot air into said washing tub to dry said tablewares which have been washed and rinsed in said washing tub.
 10. The dishwasher according to claim 9 wherein said hot air supply means comprises a casing including an air inlet port immediately above said driving means and an air exhaust port at one side of said casing, a fan contained in said casing and operatively connected to said driving means, an electric heater contained in said casing to heat air through said air inlet, and a conduit extending between said air exhaust port and washing tub for supplying thereto the air heated by said electric heater.
 11. The dishwasher according to claim 1 wherein said cabinet is provided with a door on its upper surface and a door switch operated by said door is mounted in said cabinet.
 12. The dishwasher according to claim 11 wherein said door has a removable lid portion provided with a plurality of vent holes and wherein a shielding plate is mounted beneath said removable lid portion. 